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03-23-2011, 09:07 AM   #1
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Can someone explain the 1.5 multiple to me?

I am new to this and have seen some info about some lenses having a 1.5 multiple of their focal length. I believe this has something with going from a larger sensor in 35mm film cameras to a smaller sensor in current dslr cameras. Is this correct? If so, what lenses are affected by this effect? M, K, AF, A, FA, DA? Are the images effected in any abnormal way? Thanks for the help.

03-23-2011, 09:11 AM   #2
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3 crap.factor posts in 3 days. Is this a record?

Let me google that for you

Then forget you ever heard the term.
03-23-2011, 09:11 AM   #3
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It's simple. It multiplies nothing. It doesn't matter what lens. It is there for the old 35mm people to use and sometimes complain about.

A photo you would have needed a 24mm lens to take on a 35mm camera, you now need a 16mm to get the same type of photo. That 16mm lens will always Be a 16mm lens regardless of what camera you put it on. The 1.5x means nothing beyond that.

03-23-2011, 09:48 AM   #4
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I found a nice link explaining this this.Crop Factor (Focal Length Multiplier) | Tutorial9 It is hard to get info from the forums when you do not know what the term is called. Sometimes you just get more confused searching. Thanks for pointing me in the right direction.

03-23-2011, 02:50 PM   #5
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I know you older members get tired of hearing these questions. But please play nice with us new people.

Frankly now that I have started to understand the whole darn thing, I don't know why it was ever brought up. It creates nothing but confusion for the new digital user. So the image capture is a little bigger, crop the darn thing to what you want.

@ratm4484 The image you capture would be the same view you would have gotten using the older film cameras. It really means nothing except for when you may be shooting in close quarters where you can not move. You might need a 35mm to take the same picture you could have taken with 50mm film camera.
03-23-2011, 07:01 PM   #6
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You've done well to grasp the stupidity of the whole issue in 4 posts.
03-24-2011, 01:56 AM   #7
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You're quite right, but I LIKE the crop factor!

QuoteOriginally posted by Colbyt Quote
Frankly now that I have started to understand the whole darn thing, I don't know why it was ever brought up. It creates nothing but confusion for the new digital user...
You're quite right: for the new user who has never known the 35mm film days, it's totally counter-productive, so should be absolutely ignored by anyone in that category.

HOWEVER, it can be useful for someone who is familiar with 35mm film cameras, but new to DSLRs. Personally, I've taken a far greater number of shots with a 35mm film camera than with my relatively new APS-C DSLR. So for me, for example, when I hear the term "wide-angle lens", the figure of 28mm instinctively flashes in my head - fine for a film camera, but I can immediately use the crop factor to tell me I should be thinking 18mm-ish instead.

Continuing with the 28mm lens as an example, note that these are often described as "wide-angle" by sellers of old lenses, but of course, they're won't be wide-angle on a DSLR. You can use the crop factor to deduce that these will in fact work as a "normal" lens, offering a FOV and perspective similar to the human eye.

The other use for the dreaded crop factor is, I suppose, in the field of P&S cameras. Here, you have a wide range of sensor sizes, so I suppose it makes some sort of sense to normalise focal lengths to "35mm equivalents".

Now, if you're an inexperienced photographer, you must immediately erase from mind the last 3 paragraphs, just bear in mind that descriptive terms (eg. "wide-angle", "portrait"...) for vintage lenses will not necessarily be appropriate for your DSLR!
03-24-2011, 05:34 AM   #8
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Very valid points m42man.

The problem may well be in how it published. Or should I say mis-published. I am going to keep wrestling with the concept until I can boil it down to one coherent sentence that makes sense to me and anyone I repeat it to.

03-24-2011, 08:31 AM   #9
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I'm one of those who finds the concept incredible useful, but terribly misunderstood.

There really *is* a point to understanding that a 50mm lens behaves different on your new DSLR than it does on other cameras. This isn't just useful for people who actually *shot* 35mm film; it's also useful for anyone who ever *converses* with anyone who shoots 35mm film or FF digital, or who *reads* anything written from that perspective.

But of course, the knowledge is useless if it isn't properly understood, and that's the real problem here. So I kind of wish some of the energy that sometimes goes into rants against whole concept could be redirected instead into making the concept more clearly understood.

To me, "crop factor" is exactly like converting from thinking in terms of miles and fahrenheit and dollars while in the US to thinking in terms of kilometers and celsius and euro while in Europe (not that I've had that opportunity but once). No point thinking about any of that if you spend all you time in only one of those places and conversing with and reading about that place only, but who would argue it doesn't make sense to understand the conversion when actually traveling or corresponding or reading about other cultures?
03-24-2011, 09:29 AM   #10
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QuoteOriginally posted by Marc Sabatella Quote
I'm one of those who finds the concept incredible useful, but terribly misunderstood.
And that's the problem -- It's confusing. It's a little knowledge; dangerous stuff. It's a trap that has successfully snared many. It's trying to equate the unequal.

The simple part: Yes, camera+lens+distance can be used such that different format cameras can produce roughly equivalent pictures. The confusing parts: The pictures will be only roughly equivalent. And moving a lens from one camera to another doesn't change its focal length, despite crap.factor numbers.

A concept that is so widely misunderstood is a bad concept.

I'll propose a mutant term: CHOP FACTOR. That's the amount of an image that is chopped-off by the edges of a film or digital frame. It's the brutal reality.
03-24-2011, 09:38 AM   #11
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then lets standardize the chop factor rico and start at 8x10 since everything is chopped down from the biggest format

In reality there is a need to simplify some things and when the switch was made from film to digital there needed to be a simple way to convey a difference (i was selling them then and the ds was bought the week it came out) truthfully now it becomes a matter of confusion as most users never shot 35mm so it raises questions like this regularly
annoying for those of us who have heard the explanation a thousand times but helpful to the noob trying to find there way. better that we have patience and explain again and again and add to the pool of people who can cover the explanations for us so we can stop.
I don't mind a new digital guy learning a little about the difference in how a lens performs on a format, you never know who will be enticed and by into film giving you a market for the film bodies that accumulate in your lens quest
03-24-2011, 10:53 AM - 1 Like   #12
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QuoteOriginally posted by eddie1960 Quote
In reality there is a need to simplify some things and when the switch was made from film to digital there needed to be a simple way to convey a difference
...
annoying for those of us who have heard the explanation a thousand times but helpful to the noob trying to find there way.
And I don't buy the "switch from film to digital" thang, because multiple formats have existed for a long time, but the marketing term crap.factor is maybe a decade old. So, some history.

First, half-frame (~APS-C size) was the original standard for 35mm film -- that's the size of a cine frame. From a cine viewpoint, what we call FF is actually double-frame.

Next, even after full-frame 35mm (135/FF, 36x24mm) became popular, half-frame (135/HF, 24x18mm) remained popular. I have a circa-1940 HF RF sitting on my shelf now. In the past I owned circa-1960 Canon HF RF's, and a circa-1970 Olympus HF SLR -- which could take 135/FF lenses, exactly like dropping a Tak onto a Kr now.

And, putting larger-format lenses onto smaller-format cameras is nothing new. It goes back to the early days of photography.

Using any format, one learns which lenses will do what. That's not hard. Previous generations managed to transition between camera formats without dealing with crap.factor quandaries. So why introduce the term for this generation? Have people become stupider? (Intelligence tests suggest the opposite.)

My hypothesis is that the marketing terms crap.factor and equivalence are very useful to camera- and lens-makers. They forge expectations that can't be met. Hay, this dSLR and my old P&S are supposed to have equivalent lenses, but my dSLR lens isn't sharp! (Vastly different DOF.) The kit lens sucks! The customer is induced to buy more expensive lenses.) Hay, this 50mm lens is really 75mm 'cause it's on a crop body! And when I buy a 70mm, it's really a 105mm! (Wrong.)

The confusion is epidemic -- that's why we get the same questions, repeated endlessly. The confusion is profitable -- that's why it's still promulgated. The confusion is unnecessary, but seemingly unavoidable. We are doomed.
03-24-2011, 11:10 AM   #13
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the reality is Rico you aren't the norm. most people moving over who had an SLR before, probably only ever had the one, maybe 2 and weren't versed in all the other things that existed (or had existed) I spent over 25 years at retail and believe me most clients were next to clueless on most things. that was why it was important to have a knowledgeable sales force to help them. Still is but the big boxes killed that in the pursuit of greater profits. most good indies still have decent sales people who know what they are doing.
with the move to digital there was a need to explain the difference to the guy who was a casual shooter but knew enough that when he put a 28 on the dslr it didn't do the same thing it did on his film camera (give a wider FOV) so some idiot came up with the crop factor, which does ignore other things but in essence boils it down to something a casual experienced shooter would understand. now that it's out there all these people who never shot 35 are coming in doing a little research on the web and getting confused by what they are reading. too late bud the genie is out of the bottle
and unless you know a way to wipe the web of references there is no way to change that. so you can ignore the confusion or continue to step in and give your explanation.
isn't there a well written Sticky already on this we could just point people in the direction of?

Edit: it would be nice if things were explained in a FOV model that would make sense across the formats. I want this FOV so on 35 i need this apsc that and yet another for my 645 and 6x7
I'm not sure many people who move to SLR even know why they just want better pictures but have no idea how to make them. then they have problems shooting the way they used to and getting the same effect. forgetting of course that the reason they spent more was to move on from that effect and go to something different. SLRS are crappy snapshot cameras i think, they were built to do better. the ps cameras out there take some pretty amazing snapshots with no user knowledge on the other hand

Last edited by eddie1960; 03-24-2011 at 11:16 AM.
03-24-2011, 11:40 AM   #14
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I agree with what Eddie is saying here. Yes, there have always been multiple formats, and people have had to deal with it. But there are some * very* important differences.

One, the number of people who actually owned interchangeable-lens cameras of more than one format has always been miniscule, and practically every single one of them is/was a professional photographer. The term "crop factor" wouldn't have been needed to represent the difference between formats to the masses of consumers for those cameras, because there *were no masses of consumers* for most of these these cameras.

Two, back in the days before the 135 format became the norm, there would have been no obvious single point of reference to use in applying a factor to. I'm sure back when the "full frame" 35mm format took over from the "half frame" format, there probably *was* a small circle of people who did think in terms of focal length multipliers; there just wasn't a big deal made of it because there were so many formats and so few photographers that there would have been no point. Whereas if you went to a bookstore just before the introduction of the first Canon Rebel and looked at the books on cameras and photographic technique, I'd wager 99% of those books would talking about one format and one format only: 135 format. I'd further wager that 99% of non-professional photographers who had ever used an interchangeable lens camera had used one and only one format: 135. There was a *huge* and *completely unprecendented* momentum behind this format among consumers going into the 21st century, and hence an obvious point of reference to apply the "crop factor" concept two.

Three, at how many points in history have there been two different camera lines of different format sizes but the same mount type, and thus designed to work with the exact same lenses (no adapter required)? And how popular were either of those camera lines? I'm going to guess we're not talking about something that happened very often, or with the impact of this happening simultaneously with the Canon, Nikon, Minolta, Olympus, and Pentax SLR lines at the start of the DSLR age.

So again, we now have a huge group of non-professional consumers buying interchangeable lens cameras that we have not had before, we have an obvious point of reference for the "crop factor" that we never had before, and we have tens of millions of current lenses in current use that actually fit two different popular formats with no adapter required - something that has probably never happened before.

So is it any wonder that the term "crop factor" might not have been in vogue 50 years but has a very natural reason for existence today?

And while I agree it causes confusion I say it's because it is poorly understand. Were it possible (and common) to see it explained clearly and well, then it would actually 8avoid* a ton of the confusion that would otherwise exist as people bought books on photography written in the 1990's and then wondered why the lenses sold with their cameras were of entirely different focal lengths than the ones discussed in the books, and start buying inappropriate lenses.
03-24-2011, 12:48 PM   #15
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The thing that confused me the most when I started switching to digital was if only the FOV changed. I too wondered how far the "equivalent" went. What I mean by that is if you'll get the same wide angle distortion on let's say, a Sigma 10-20, close up on a subject on an FF camera as with an APS-C. I figured you would at the same distance BUT since the crop factor will require you to back up to get your whole subject in frame then it will affect it, at least by a small amount.

Same thing goes for telephoto compression. You pop a 100 mm lens on an APS-C and you'll get the compression and DOF of a 100mm, not 260mm. Once I got that cleared up in my head it became easier to choose lenses.
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